In concrete/steel block production, mould release agent is used for lubrication during the process of detaching the moulded concrete from the mould (formwork) and prevents adhesion of freshly placed concrete to the forming surface. At present, petroleum-based fluid is used as the mould release agent. This material is normally produced in an unpleasant environment as petroleum-based mould release lubricants are used in the workplaces involving pre-cast and construction-related concreting operations. The frequent use of this oil causes health problems and has a negative environmental impact in the workplaces, as the products are flammable (with strong petrol odour), toxic and has unpleasant odour.
Due to the increased environmental awareness and ever-increasing price of the present commercial mould oil originated from petroleum-based fluid, the search for a “greener” alternative especially that can take care of the environment has been actively carried out. Moreover, employers and workers directly involved in the industry themselves are increasingly asking for building ingredients and construction processes that have a lower environmental impact due to the real health risks created by the use of the toxic lubricants and mould release agents in the workplaces. The search for non-toxic, renewable and biodegradable mould release lubricants which can be termed as “green” is indeed very important.
Previously, mould release agents were manufactured from mineral oils and waxes with incorporation of a chemical compound having good release property such as oleic acid. The mould release agents were evolved into oil-in-water emulsion (Nielsen, PCT Publication No. WO 8505066 A1, 1985) taking in the triglyceride from vegetable oil, aliphatic carboxylic acid ester, non-ionic and anionic surfactant or antioxidant and polyacrylate (Wittich et al., German Patent Publication No. 4400272 A1; 1995) to improve release of a moulded concrete piece. There was also a more advance technology of manufacturing the oil-in-water mould release agent using industrial wastes such as vegetable oils and engine oils (Yi, China Patent No. 1129633; 1996). Other vegetable oil-based mould release agent with sealing effect was also invented to prevent the passage of water into the concrete (Lightcap, U.S. Pat. No. 5,647,899; 1997). It was derived from a non-refined vegetable oil; which can be derived from sources such as, but not limited to coconut oil, corn oil, palm oil, cottonseed oil, rapeseed oil, soy oil and sunflower oil or a mixture thereof and an emulsifier. To overcome property drawbacks such as oxidation resistance, anti-wear, corrosion resistance, viscosity stability and tackiness, thus, vegetable oil can be suitably used as a mould release lubricant by formulations to incorporate proper designed specialty additives into the lubricant compositions, to suit the intended use of the lubricants formulated.
Lafay V S and Neltner S L in United States of America Patent Publication No. US 2002172759 A1 disclosed a biodegradable mould release agent comprising of vegetable oil, mineral seal oil (viscosity reducer), alcohol or mixture thereof with the incorporation of a filler and oleic acid. It could reduce adhesion between concrete and formwork or mould, thus improve the life of the forms. All the improved mould release agents invented so far exhibited chemical rather than a barrier (physical) release. This means that the mould release agents produce a thin, harmless soap between the concrete's surface and the mould itself, thus produce a smooth finish to the concrete. This will ensure less volume of mould release agents used than the traditional agents, and offers protection of steel mould casings from corrosion.
In EU, concrete release agents are usually based on rapeseed and soy oil and esters. The ‘Blue-Angel’ approved concrete release agents in Holland have been marketed successfully (distributed by Elf and Total) (Theodori et al., Concept paper on development of criteria for the award of the European Eco-label to lubricants; 2004). Although the use of vegetable oils have been highly recommended as they are renewable, biodegradable and environmentally friendly and have superior lubrication properties, they have not found wide applicability in high-performance loss lubricants such as mould release agent due to the lack of effective viscosity and oxidative stability and tackiness in its ability to release a formed material when subjected to thermal stresses from its mould compared to conventional lubricants or synthetic lubricants. Palm oil being a natural vegetable oil and with inherited lubricity property and corrosion inhibition (Loh and Choo, J. Oil Palm Research Vol. 24: 1388-1396; 2012), is a potential base fluid suitably used as an alternative to mitigate the environment issue and cost associated with the use of commercial petroleum-based mould release lubricants in current workplace. It is found effective too in preventing concrete adhesion to aluminum (Freedman, PUBLICATION # C750084 The Aberdeen Group; 1975). It is important that the proposed alternative is able to satisfy all these requirements and possibly still remains competitive.
A new mould release lubricant derived from palm olein has been pursued. Present invention concentrates on formulating palm olein and/or its derivatives having good low temperature fluidity property into a mould release agent having optimum performance fulfilling every aspect of the specifications for greener mould oil used in concrete production besides ensuring that the production process and the finished concrete units conform to higher standards and more stringent conditions and regulations. Besides being cheaper compared to other vegetable oils, the manufacturing process of palm-based mould release lubricant is rather straightforward. Thus it has a great opportunity to be emerged as a cheaper product in the market. This will open up another business opportunity to palm oil industry in adding values to palm oil.
The naturally occurring vegetable oils having utility in the present invention comprise at least one of, but not limited to palm oil, soybean oil, rapeseed oil, sunflower oil, coconut oil, canola oil, peanut oil, corn oil, cottonseed oil, safflower oil, meadow foam oil or castor oil.